﻿<p>The <em>IfcFaceBasedSurfaceModel</em> represents the a shape by connected face sets. The connected faces have a dimensionality 2 and are placed in a coordinate space of dimensionality 3.</p>
<blockquote class="extDef">NOTE&nbsp; Definition according to ISO/CD 10303-42:1992<br>
A face based surface model is described by a set of connected face sets of dimensionality 2. The connected face sets
shall not intersect except at edges and vertices, except that a face in one connected face set may overlap a face in
another connected face set, provided the face boundaries are identical. There shall be at least one connected face
set.<br>
A connected face set may exist independently of a surface model.</blockquote>
<blockquote class="note">NOTE&nbsp; Entity adapted from <strong>face_based_surface_model</strong> defined in ISO
10303-42.</blockquote>
<blockquote class="history">HISTORY&nbsp; New entity in IFC2x.</blockquote>
<p class="spec-head">Informal Propositions:</p>
<ol>
<li>The connected face sets shall not overlap or intersect except at common faces, edges or vertices.</li>
<li>The fbsm faces have dimensionality 2.</li>
</ol>

<blockquote class="deprecated">
IFC4 CHANGE&nbsp; The entity has been deprecated and shall not be used. The entity <em>IfcShellBasedSurfaceModel</em> for open shells and <em>IfcFacetedBrep</em> for closed shells shall be used instead.
</blockquote>